Resistant and susceptible lines in Brassica rapa have different immune responses against Fusarium oxysporum inoculation.

We identified the candidate gene conferring yellow wilt resistance (YR) in B. oleracea . This work will facilitate YR breeding programs for B. oleracea and its closely related species.

Fusarium yellows caused by Fusarium oxysporum f. sp. conglutinans is an important disease of Brassica worldwide. To identify a resistance (R) gene against Fusarium yellows in Chinese cabbage (Brassica rapa var. pekinensis), we analyzed differential expression at the whole genome level between resistant and susceptible inbred lines using RNA sequencing. Four hundred and eighteen genes were significantly differentially expressed, and these were enriched for genes involved in response to stress or stimulus. Seven dominant DNA markers at putative R-genes were identified. Presence and absence of the sequence of the putative R-genes, Bra012688 and Bra012689, correlated with the resistance of six inbred lines and susceptibility of four inbred lines, respectively. In F(2) populations derived from crosses between resistant and susceptible inbred lines, presence of Bra012688 and Bra012689 cosegregated with resistance, suggesting that Bra012688 and Bra012689 are good candidates for fusarium yellows resistance in Chinese cabbage.

Kupffer cells are the largest population of tissue macrophages. They are predominantly distributed in the lumen of hepatic sinusoids and exhibit endocytic activity against blood-borne materials entering the liver. Macrophage colony-stimulating factor and other growth factors regulate Kupffer cell differentiation in the fetal and adult period. Because of the unique attributes of tissue, Kupffer cells play essential roles not only in host defense but also in the homeostatic responses of tissue. Macrophage scavenger receptors and heme oxygenase are expressed in Kupffer cells from an early stage of ontogeny. Scavenger receptors are involved not only in the lipid metabolism but also in the bactericidal mechanism. Heme oxygenase in Kupffer cells is essential to the production of bilirubin. In this review, the developmental mechanism and functional activities of Kupffer cells are described. Evidence suggests that Kupffer cells represent a distinct cell population with unique differentiation mechanisms, metabolic functions, and responsiveness to inflammatory agents.

Primitive macrophages appear in the yolk sac and fetal liver, migrate into other tissues, and differentiate into fetal macrophages. In adult mice, tissue macrophages are proliferating populations distinct from monocytes. After the depletion of macrophages by the administration of liposome-entrapped dichloro-methylene diphosphonate, the repopulation of affected macrophages appears to depend upon the increase of precursors in the liver and spleen. In mice homozygous for the osteopetrosis (op) mutation, the absence of macrophage colony-stimulating factor (M-CSF) activity results in various degrees of deficiency of monocytes, macrophages, and osteoclasts, but not of dendritic cells. The administration of M-CSF to op/op mice increased the number of macrophages and osteoclasts and induced bone remodeling. Dendritic cells were generated in cultures of bone marrow cells and mononuclear cells from peripheral blood in the presence of granulocyte/macrophage colony-stimulating factor. These results indicate that the development, differentiation, and proliferation of macrophages, osteoclasts, and dendritic cells are regulated by the tissue microenvironment, including the in situ production of macrophage growth factors in both fetal and adult life.